Air-brake system.



G. MACLUSKIB. AIR BRAKE SYSTEM.

APPLICATION FILED AUG. 24, 1907.

917,091. .n Patented Apr. 6, 1909.

' BSHBETS-SHBET 1.

FIB. l.

INVENTUR 1ML EEUFIGE MAELDEKIE. y. if, WMM

i ATTN.`

G. MACLOSKIB.

AIR BRAKE SYSTEM.

APPLIOATION FILED AUG. 24, 1907.

917,091 Patented Apr. 6, 1909.

3 SHEBTS-SHEET 2.

FIGB.

" www? 4.-, Tu TRAIN n ,PIPE ZMW/l makkwum A las F Il :f

Y T 4Tm BRAKE :YLINDER WITNESEES: INVENTUR Gx-:URGE MAcmsKlf-l, mw- BWM/@www NDRRIS PEYERS. INC.. LlTHO. WASHINGTON, Dv Cv G. MACLSKIE.

AUI BRAKE SYSTEM.

APPLICATION FILED AUG.*24, 1907.

l Patented Apn, 1909. asHBE'rs-SHEBT a.

Ilm/ENTER EEDREE MAGLUSKIE,

ATTY

NURIUS PETERS. INC LTHD WASHINGTON. D C

cierran sierras 'amaai-diarios.

leiioieen MAOLOsKin-Oi soiiENEeriiir/r, New YORnAssi-GNOR ro GENERAL retro-Taio coMrANY, .i CORPORATION or YORK.

ain-BRAKE sYs'rEM.

No. 917,091.l

Specification of Letters Patent.

Patented April 6, 1909.

l Application f ld AuguSt'Z, 1907. Serial No. 390.063.

To all whom it may'con-ccrn:

Be it known that I,vr GEORGE MAOLOsKIELa citizen of the United States, residing at Schenectady, county of Schenectady, State 1NewYork, have invente'dcertain neuvv and l -useful Improvements .in AirB1a.le tystems,`

ing also so designed that the pressure in all the .brake cylinders Will be equal notwithl'erent brake-cylinder pistons.

In carrying my invention into effect, I

make use of a main valve having ports for controlling thesupply of'air to ant for operating said valve, ythe piston chamber bein@- chanber on one side of the piston and'vvith the train pipe on the other, a reservoir carry. at substantially constant pressure, a.

ing air controlling valve controlling the supply of air from said reservoir to the valve chamber of the main valve, and means for operating said controllingvalve controlled in accord.

ancefwith variations in'` the brake cylinder pressure. the operating to a substantially uniform pressure, reservoir pressure,.opposed.gto the sum of brake cylinderpressure andthe pressure in the chamber of the .main valve. Bymeans of this arrangement-'a predetermined lowerin and raising of the train pipe pressure results ina proportionate increase Orldecrease of brakecylin'der pressure and when that proportionate increase or decrease has ac. curred the controlling valveis closed Or opened asfthe case may be andthe main i valve is immediately returned to lap-posi# 45 tion.

means for the controlling valve My invention will best be understood reference to the following',sp'eciiication, i and to 'the accompanying drawings, in Which- Figure 1 represents diagrammatically any automatic air-brake syst-ein arranged in acl cordance with my invention; vFig-1 Z'sfn'ovsfe somewhat diagrammatically the automatic `t-alves in simplest torni shown in cross-seni. tion; Fig. 3 shows a* cross-sectional y'v1e'vv`ofthe automatic valvemech'anism in -itspreof this character by means of which a grad-- 'standing differences in the travel of the dif? the re-v lease of air from the brake cylinder, a piston in communication With the valvel More speci'lically stated, I' subject such as Y ferred forinand-Figs. l to 7, inclusive. show I detailviews of the main valve in its .several positions. l In Fig/1I haveshouii'my applied tol 'an velectrically o g ieri comotive, and conscdivr "fha Y lriven compressori ivliicli'is sup plied out switch and controlled by a pressure governor-Fl, This compressor supplies the mainreservoir 5Which is connect-cdihrough the usual reducing valve G and cher r valve T to the service reservoir lt is, of course uunecess'ary to have a main source of air suppl;v `on each car of the train, but in any case ull the service reservoirs must either be Colinectedto a main reservoir or .other source ol' substantially constant pressure, or` il' charged through one or more brake applications. Theconstant pressure desired may iie conveniently, obtained connecting all the main and service reservoirs to a reservoirlino vgineers Aormotornians valves, which are connectedlto.reservoir-line'Q, and also to tlie .trani-pipe 11. 12. represents a casing' coutaming the main valve and the -controlling valve, the details of which will be hereafter described..` Pipe 'connections extend' from 'this casino to the train-pipe 11,'to reservoir 8, and toflbrakecylinder 13.

form in vFig. 2. ln this figure, .represents a slide-valve i'vhichv l term the 4niaiii valve. actuated by. the pistonl, which is exposed on itsgleft-hand side toA train-pipe pressure. :anden its right-hand side is open to the umiu' valve chamber. This chamber instead o'i be ing connected to a service reservoir asin the ordinary automatic system, is connected through pipe-connection 19 to a port controlled by the slide-valve 20 operated by th:`

iston 21, and to the chamber'on the lol'tand side of piston 21'. The sdo-valvo 20. which I term the controlling val.'e,r .-utrols the connection l'roin mainreservoir, which is connected to the chamber on the right-hand sid-e of pistou 21, throughthe pipe'lQ to the irrentY through v'the trolley 2 andwu-4 The arrangement of the main valve and the controlling v'alveis shown in its simplest v from the train-pipe, inust be large eiiough to maintain a substantially constant pressure" il l) side to the pressure inthe chaniheroi the' main valve. 4The slide-valve 2O is' operated lrgfpistzonv 21 and also by a smaller piston 2G atmosphere on its right-hand side, while its lefthand side is connected through pipe 28 to `brake-cylinder, thegstem oli piston 26 abuttingagainst pistoni '21. 2.1 and 26,'l consequently, form for the controlling-valve 2O an operating vneehanism subjected lto reservoir pressure opposed to the sum ofy brake-cylinder pressure vand 4the pressure'in the chamber` of the mainvalve 13.

l The operation of the valves is as follows: To applylthefbrakes, the pressure in the trainpipe!` 'is lowered a predetermined amount. .Piston 15 is consequently--niove l tothe left, shifting valve 13 and thereby disconnecting brakecylinder from port 17 leadingto atmosphere,` and connecting it to the vhamher of valve l3 ,Since this chamber is connected' through' pipe to'th-e chamber on the lefthandslde of p1ston 21 the pressure in. the latter chamber is lowered therelov causing valve J v L.

20 to he'moved to the left and connecting reservoir to brake-cylinder. The pre sure in the brake-eylinder rises until it reati es an amount which, acting onfpiston 2S and assisting the` pressure on the left-hand side oi returns valve 20 to theposition shown.

vpiston 21, overp'owers reservoir pressure anl further slight flow of airlrom the ehamher en the right-hand vside of piston 15 to .brakec'ylinder reduces the pressure in that 'Chaniber and causespiston 15 to return toward the position shown, far enough to move the valve 131to lap'fp'osition. A further reduction of train-pipe pressure results ina repetition of the operations' above described.-

.1f it is desired to release the brakesin part, the pressure in the train-pipe is partiallyT restored.- This causes piston 15 to move to the position shown 'in Fig. 2, connecting brake cylinder to atmosphere through port 17, and lowering the brake-cylinder pressure. When the brake-cylinder pressure falls a certain amount, correspondingly reducing the 'pressure on piston 26,'.reserv'oir pressure on the right o' pist-on 21 over-balances the two f pressures that opposeA it, and Causes valve 2 0 further' increase in train-pipe pressure results in a repetition of this operation. 1t will be seen-that both in ajp lieation and 1n the" rethe brakest e brake-cylinder presiy .i unted ina piston chamber which 1s open to V vembody my invention is shown in -eross-see- The two pistons- `form of connection is that 'byaits use-leakage' from one piston to the other or -frornpiston f 2'1 to atmosphere is prevented, since the-'105".

.lower side the' sha e of which is shown ini sure determines the movement of the valves to lap-position, so hat the same pressure' is obtained in all the brake cylinders on the train, regardless ot' chile-reneesl in the travels of the brake-cylinder pistons.

The preferred construction of the main valve and of the controlling valve Which tion in' Fig. 3. In this figure, 13 represe the main valve proper and le the Oradua 1n valve; both of which are operated h v the piston 15. A portl in the valve-seat leads .to the brake cylinder; another port 17 leads.

Ain Which the valve 20 moves are conneoted through a passage 22 to the servite reservoir .or other source of airunder suhstantialhT constant pressure. represents a 'pin-.orl shaft journaled in the tva-ll of the easing containing the piston 21, having one arm 24- Wit'hin the casing engaging the spindle ofv valve 20} While another arm 25 outside the Casing engages the spindlelof a piston 26, which is in a second hamherfor easing sep# arate from that in Whieh 'the piston 21 moves. The shaft 23, vWith the arms 241 and 25, forms and 26. The advantage of this particularv opening 4inthe easing throughwh'iehthe pin; s 23 passes may readily be made" air tightfli The right-hand'sid'e of vpiston 26 is o en toA j atmospherev through a s r'n'all hole 27 1n the easing, While the left-handsid'e oi the i's'tjonv 1'1'0 is connected by a-passage 2 8toa' smal ,aux-l iliary port 29 in thesea'tof the main valve. This auxiliary port -29 is @ermee-ted by a' ref stricted'- passage 2 9, shown in'Figs. 1 to 7,

with the -mainport 16 leading to -brake- 115' 'cylinder'.

' The 'main valvei" is lprovided With an -L-- i -shaped'port {f3-0 and tivo airsof ports 31 and l32, and 31 and 32', of W uch each pair is arv *ranged to register with the'p'orts 16 and 29, 12ol in the valve-seat in one position of theinain valverg.' The' graduating valve 141s pro* vided With a'chamher orpassage 33 initsdotted lines-in Figsf to 7.

.lhe operation. o'the 'valve meeh'anisin above desc rihed,'is asffollows:V Fig'. 3 shows v all thep'arts in' running or releese'position,

-the'po'sitions :of the main and graduatirg:-'4 -valve'with respec-tto the ports' 1nv the valve-.130

10ov a bell-crank lever connecting the pistons 21.

wakes a certain reduction of. re-ssure is ade in'` the .train-pipe. rThis owersthe ve to the left, shitting the graduating valve and then `the main val-ve vtoward the pesiticn shown in Fig. 6,' which shows the. extreme osition of the valves for emer-v gency app ication.-

i and 32 in.' the-main valve 13 register with the por-'ts 16 and 29 in the valve-seat. For ordinary service applications the registry ci these valves .is only partial. The piston le chamber at the right-hand side of thepiston 1-5` is `ut in. communication with the brakevcy'iin' er through vort 16 and with the piston chamber at thelilft-hand side of piston 26 through'port 29- and passage 28. This re-. 'suits inl lowering the pressure on the righthandside ofthe piston 15, and this reduction of pressure is communicated through passage 1-9 to the right-hand side of piston21, so that before the pressure on theright-hand sideofpiston '15 has been materially reduced the piston 21 movsto the right, shifting valve 26 and placing reservoir in communication with iston and with-` brake cylinder t'woug .passage 22, valve 20, passage 1'9, part 31 and port 16. reservoir is connected to: the lefthand side of piston 26, so that the pressure in brakecylinder and in the space to thedeft of pisvton 26 rise together.

. stricted assage between ports 29 and' 16 in the main valve-seat. the brake-cylinder and consequently on the Y left-hand side of the piston- 26 has reached a certain amount, the pressure on piston 26 asl sisting the pressure on the right-hand of piston 21, again balances reservoir pressure on the left-hand side of piston 21, so that valve 20-is returned to the position shown in l.- ig. 3 cutting off the reservoir from the chamber'of the main valve, so that a further small flow of air to brake-cylinder equalizes the pressure on Vthe opposite side o t piston 15 and the piston and graduating valve14 are '.i returned to la y-position, as shown in Fig. '7. e further rec notion of train-pipe lpressure results in a re etition of the operations just described, an( an increase of brake-c Tlinde-r pressure. To release the brakes partially, the ressure in the train-pipe is increased a s rna l amount. This causes the pistonv15 to movev tothe right, returningy the mainland,

graduating valves to the position shown Fig. 3 and Fig.- 4.. In this position ports 29 toand 16, in communication with the left-hand side of ypiston 26 and with brake-cylinder, respectively, are connected yto atmosphere through ports ,31 and 32, chamber' 33, port 30 and port'17. The pressure both 1n the 65.

ssure on the left-:hand side ci' the pistonci the main valve, causing the piston toln this position the ports l At the same time' Equalization between these pressures is maintained by. the re- When the pressure inbrake cylinder and on the lef-trhand side of v piston 26 consequentlyl falls, untilY the sum of the pressures,- due to brake-cylinder pres sure onthe piston 26 and the pressure. onthe right-hand side ofpiston 21;, falls below the reservoir-pressure on the left-handl side ofv piston 21. Whenv this occurs, piston 21 moves to the right, opening valve 20, coni necting reservolr 22 momentarily to the' valve chamber on the right-hand side of .piston 15, so as to. cause this piston to move the graduating valve to llap position, as shown in Fig. 5. sure rises onthe.right-hand side of piston 212,. so as to return val-ve 20 and-cut ed the reservoir from the main valve chamber- Further increase 'of trainfpipepressure results in a repetition ofthe above describedr operations, and' in a further reduction of brake-cylinder pressure. In this manner, a graduated re* lease of the brakes is obtained as effectively as in a straight-air system, and furthermore, the pressuresinall the brake-cylinders are equal, regardless of differences in .pistontravel ofthe brake cylinders, sincey the opera.

ltion ofthe valves is controlled by the pres-- comparatively greater Avariatifm of pressure j1n brake cyllnder.

For instance, il the effective area of piston 21 istwice that of piston 26, a reduction ofiive pounds in the train-pipe will give an increase of ten pounds in the brake-cy inder. p

'l he purpose-of providing an auxiliary port in the main valve connected to the lefthand side of piston 26, is to make the rise and fall At thesame time the pres'- l of pressure on this piston, and consequently the' operation of the piston, more deiinite' than wouldbe possible if the connection to this piston were made only froml the passage leading to the 'brake cylinder, since inV the latter case the flow of air through that passage would produce false pressure-variations on the piston. these disturbing effects are avoided vby the use of the auxiliary port 29 in i the valve-seat of the main valve. It will be noticed that tl'legraduating valve la is soarranged that in moving from application positionshown in Fig. 6 to lap-position shown y Ain Fig. 7, and back again to application position', ports 16 and 29 are opened and closed simultaneously. release position shown in Fig. 4 to lap-position shown in Fig. 5, and back again to releaseposition, ports 16 and. 29 are opened and closed simultaneously. The restricted connection between ports 29'and 16 serves to Similarly, in moving from maintain an equalization of brake-cylinder y pressure and the pressure' on piston 26, both during increase and reduction of pressure,v

and also during prolonged brake-applications whenleakage either from brake cylinder or from the space at the left ot" piston 26 might occur. j p

l reo Leakage around the piston l5, by Which the main valve 1s operated, affects, of course, the sensitiveness ot' operation of the system and since it is practically impossible in a Working system to avoidsome leakage around this piston, I prefer toy give the valve chamber of the main valve suflicient capacity so that it will act as a pressure equalizer' and prevent such a. leakage of air as is likely to occur in practice from allecting the movevment of the' main valve in response to changes in train-pipe pressure. f Instead of enlarging the valve chamber itsell,'I prefer in practice to connect to it a small 'reservoir having the requisite capacity for the purpose above described. Such al reservoir shown at Stin Fig. 1' and the pipe connection from j the main valve chamber to this reservoir is shoyvn at 85 in Fig. 3. In practice the capacityof the main valve chamber should be made large enough so that the valve will quickly respond to a desired variation of train-pipe pressure and the larger the capacity ofthe chamber the smaller will be the variation in train-pipe pressure requisite to produce a movement of the valve. practical operation I have found that a very small capacity is sufficient for this purpose.

\ l What I claim as new` and desire to secure by Letters Patent-of the United States, is,-

l. An automatic air-.brake system, comprising a brake cylinder, a train-pipe, a main valveprovided with ports 'for controlling the supply of air to and the release of air-from the brake cylinder, a piston foroperating said valve, the ist-on chamber being in communisure in the brake cylinder for controlling the operation of safidy controlling valve.

2. An air-brake system comprising a reservoir containingv air under, substantially constant pressure, a brake cylinder, a trainpipe, a main valve and a' controlling valve controlling the lsupply of air to,andv the eX- haust of air from said brake cylinder, the

main valve having ports connected to brake cylinder and atmosphere and being provided with an operating piston connected on the one side tothe train-pipe and on the other side to the chamber of said valve, and the controlling valve controlling the connection between the reservoir and the valve chamber of the main valve, thecontrolling valve being provided with a piston connected on one side to its ovvn valve chamber and on the other side to the valve chamber of the main valve, and a second piston fory closing the control- 'ling valve connected on one side to the brake.

cylinder andI on the other side to atmosphere.

Forv

3. An automatic air-brakelv 'system comprising a brake cylinder, a train-pipe, a main valve provided. With ports for controlling the supply of air to and the release of air rom the brake cylinder, a piston Jfor operating said valve, the pistonV chamber being in communication With the valve chamber on one side of the piston and With ythe train-pipe on the other, a reservoir containing air under substantially constant pressure, a controlling valve for controlling the supply of air from said reservoir tol the valve chamber of the main valve, and ,operating eans therefor subjected to a substantially u `iform pressure opposed to the sum of brakeeylinder'pressure and a pressure proportional to the pressure in the valve chamber of the main valve.

4t. An automatic-iair-brake system comprising a brake cylinder, a train-pipe, a main valve provided with ports for controlling the supply of air to and the release of air from the brake cylinder, a piston. for operating said valve, the piston chamber being in communication With the valve chamber on one side of the piston and with the train-pipe on the other, a reservoir containing air under substantially constant pressure, a controlling valve for controlling the sup ly of air from said reservoir to the valve c amber of the main' valve, and operating means therefor subjected to a substantially uniform pres-A sure opposed to' the sum of brake-cylinder. pressure and the pressure in the valve chamber of the main valve, the ellective area subjected .tol brake-cylinder pressure being less than'that subjectedto the pressure in the chamber ofthe main valve:

l 5. An automatic air-brake systemcomprising abrake cylinder, a .train-pipe, a main valve'provided with ports for controlling the supplyfof air to and t 1e release of air 'from the brake cylinder, 'a piston for operating said valve, the piston chamber being in communication With the valve chamber onone'side of the pistonand with the train-pipe on thel other, a reservoir containing `air under-substantially constant pressure, a controlling valve for controlling the supply of .air from said reservoir to the valve chamberof 4the main valve, and .operating means therefor subjected to reservoir pressure :opposed to the sum of brake cylinder pressure and a. pressure proportional to the pressure in the chamber of themain valve, the eiiective area subjected to brake-cylinder ressure being valve, the iston chamber being in'communication Wit the valvechamber on one side of the piston and With the train-pipeon the 'less than that subjected tot e pressure, 1n f 5o valve provided With ports for controlling the other, a reservoir containing air under 'subprising a brake cylinder, a trani-pipe, a main valve provided with orts' for'controlling they sup ly of air to and e release of'air from the bra .e cylinder, va piston for operating rsaid valve, the piston chamber being lcommuni-` the valve chamber joli-one Side of theA piston and Witlithe train-'pipe on the other, a reservoir containing air under sub.- stantially lconstant pressnrfef a controlling valve for controlling thesup ly oigair from said. reservoir to the valve. cnamber of the main valve', meansV controlled by the l'brake-v cylinder Preseglie QI Centralina Said @01112.101.- valve, the wie valve'fbnspi'ovded an .axiliary port @enacted .to Said .0.01.1- trolling means, and a restricted vconnection between Said auxiliary port and the main port ,leading to brakecylinder; 8'. An automatic' air-brakesystem com pricing a brake cylinder, @train-pipea mainb @life Pradd Withfporis for controlling the.

'40 the mamvalv; means Centro cciitrollin i snpplyof air lto and= the release of air from -i111?!'lc'frake cylinder,` a .piston for operatingA said valve, the pis'ton .chamber being in communication Wit thevalve chamber.. on one.Y

I side of the piston y'With the train-pipeon thel other, a reservoir ..containing air under Silhstantallrwstant pressure a Controllin'gralve far @patrolling .the .Supply 0f, air from said reseroir tio tlievalve hamber o f L 1 ,lied by ne: brakecylinder' pressure for' contrQllIlg 'saidvalve, `the'main valve' being ro'.-

. vidadwt an auxiliary `part@IlilccteA. t0.

.Said @O rtlliag @abrirle arreaed tofopen and fclose said auxlliary port slmul-4 ltan'eously' with 'the opening 4andclosing ofA the main port 'leading to brake cylinder.

9. A n automatic air-brake system\ comprising a brake cylinder, v-a train-pipe, a mamsupply of air to and thel release of air from' the brake cylinder, a Apiston -for operating said valve, the iston chamber'being in communication Wit the valve chamber on one side of the piston and .with the train-pipe on the other, a vreservoir `containing air. under' Substantially constant. pressure, a' controlvalve for controlling the supply of air from said reservoir .to the valve chamber of the main valve, means controlled by the brakeecylinder pressure for controlling vsaid Said @html-lieg means, and .being arranged.

the main'port leading to brake Gylldli Mld iary port and said main ort.

prisingabrake cylinder, atrainpipe,l a main valve provided with ports for controlling the. supply of air to and ithe release of air from -the brake cylinder, a piston for operating said valve, the piston chamber being in communication with the valve chambe'ron one from' s'aid` reservoir to the valve chamber of .the-main valve, and operating means therepressure opposed tov the fsum' lof brake-cylinder pressure and-the pressure in the chamber of the main valve, themain valve being -provided With an auxiliary port opening into. the passage by. 'which brakecylinder pres'- sureis conveyed *to saidoperatin -n1eans andbeing arranged l'to' open .ando ose said auxilizfiryA lport 'simultaneously with the opening and 'closing .ofthe mll Port.. lead# ing to brake. cylinder? 11.1- .An @tomada air-brake .System-eemprsng @brake Cylinder, a train-Pipa@ .man valve provided with ports for controllin the supply-'ol= air to and the release of air 179m thebrake yc linder, va piston for operating .saidvalve, tlie iston chamber being in communication Wit the valve chamber on one side ofthe piston and' with the train-pipe on the other, a reservoir containing air under valve forcontrolling t. ve Sup ly of air from main valve, operating means therefor subjected to a substantially uniform ressure' opposed to the sum of brake-cylin fer pres- .surfe and a pressure pro ortional to the pressure in the chambar o the main valve, the main valve being provided with an auxiliary vport opening intothe passage b Wlnc operating means and being arranged to open and close said I,auxilia port simultaneously with the opening and c osing of the main port leading to brake cylinder, and a restricted connection between said auxiliary port and said main port.

' '12.. :automatic air-brake system comprising a brake cylinder, a train-pipe, a mam valve provided With ports for controllin the supply of air to andthe release of air rom` vthe brake c linder, a' piston for operating munication Wit the 'valve chamber o n one valve, themen valve being vided Wit.. an aarliary Port @acacia te eide 'eff die piston and with the 'maia-Pira Q11 to open and close said auxiliary port'siinul-.- taneously with the opening and closing of arrestricted connection between said' auxilv 7.o 10. An automatic airur 'ke system coniside of thair piston and with the train-'pipe on 'the other, a reservoir containing air under substantially constant pressure, a control` ling valve vfor,controlling 'the' supplyof air'4 i'or subjected to a.'substantially uniform substantially. constant ressure, av controlling Sald'reservcirto the valve c amber of the rake-cylinder'pressure is conveyey to said said valve, t e iston chamber being com? 10. ing having one arm inside the casing opera# l .tively connected to said piston and a second arm outside the casing, 'a second casing inclosf' mg the second arm, and va piston Within the 'second casing 'operatively connected to the "1:5, second arm and subjected-to brake-cylinder pressure.

1 3.l an automatic air-brake system, a casing, a valve' therein, an operating piston 'f for'said valve subjected to opposing pres v120 sures, ja' bell-crank lever j ournaled in the cas- 'ing` having one arm inside the casing operatively connected to said piston and a second l arm outside the casing, a second casing in- `Closing'thesecond arm, landa piston Within Z5 the second casing operatively connected to ",thefsecond armw l `14., automatic air-.brake system, coml"ifpifisil'lgf a reservoir containing air under sub- .'staiitially constant pressure, a brake cylinteder, a train-pipe, a main valve provided with 'ports for controlling the supply of air to and "the release of. air from the brake cylinder, a piston for operating the said valve, the piston -olla-mbar' being in communication with the '3 5 ryalvechamber on one side of the piston and with theitrainspipe on Athe other, a controlfling valve for controlling the supply fof air from said reservoir to the valve chamber of l fthe main valve, an operating piston therefor, feci-having its piston chamber subjected on one sidelv to reservoir pressure and on the other -side to the pressure in the chamber of the main valve, and a second piston operatively connected to the controlling valve, the piston chamber of said second piston being connectl edfon one side to atmos here and on the other side tothe brake-'cy "rider, f. 15;; An 'automatic-air-.bralre' system coni- 'I RITV-isnga reservoir containingair under sub- 4stantially'constant pressure, a brake Acylinder, a train-pipe, a main valve rovide'd withpor-ts for controlling the sup y of air second piston operatively connected to the controlling valve, the piston chamber of said secondpiston being connected to the brake cylinder through a restricted passage. 16. An autoniaticair-bralresystem comprising a reservoir containing air under substantially constant pressure, a brake cylinder, .a .train-pipe, a' main valve rovided With ports for controlling the sup ly of air to and the release "of air from t e brake cylinder, a piston for operating the said valve, the piston chamber being in communication With the .valve chamber o n one side of the piston and with the train-pipe onthe other,y a controlling' valve for controlling the supplyv of air from said vreservoir tlthe valve chamber of the main valve, an operating piston therefor; having its piston chamber subjected on one side to reservoir pressure and on the other side to a ressure proportional tothe pressure in the c amber of the main valve, and a second piston operatively connected tov the controlling valve, the piston chamber'of said second pist-on being connected through a restricted passage to `the brake cylinder when the main valve is in its release position and to the main valve chamber When the main valve is in its application position. 17. An automatic air-brake system comprising a reservoir containing air under substantially constant pressure, a brake cylinder, -a train-pipe, a main ,valve rovided Awith ports for controlling the suppllgy of air to and the release of air from the brake cylinder, a piston4 for operating the said valve, the piston chamber beingin communication with the valve chamber on one side of the piston and'With the trainpipe on the other, acontrolling valve for controlling the su ply of air-from said reservoir .to the valve ciamber of the main valve, an operating piston therefor, having its piston chamber subjected on one side to reservoir pressure and on the other. side to the pressure in the chamber of the main valve, and a second piston operatively connectedk to said controlling 'valve and vhaving its piston chamber connected to brake cylinder, said second piston being of smaller area than the operating piston of said valve. y

y18. An automatic air brake system coniprising a reservoir containing fair under substantially constant pressure, va brake cyl- Iinder, atrain-pipe, a main 4valve provided Withports for controlling thersup y of air 120 to and the release of 4air from t e .bralre cylinder, al iston ,'foroperating the said valve, the plston chamber being 1n communication With the valve chamber' on one side of thepiston and Withv rthe'train-pipe 125 on the other, a controlling'yalve for con- A trolling the su ply y0f= air-from 'said reservoirv to the valvec amber of themain va1ve,j--an 'fol operating piston therefor, having its piston seat of the main valve communicating with 1o chamber subjected on one side to reservoir said passage. pressure and on the other side to a pressure, In Witness whereof, I have hereunto set poportonal to the pressure n the chajmber my hand this 23rd day of August, 1907.

o' the main va ve, a secon iston o erav tively connected to the controling vallee, a, GEORGE MACLOSKIE restricted passage connecting the piston Witnesses:

chamber ofsaid second piston to the brake HELEN ORFORD,

cylinder connection, and a port in the valve ABBA B. MARVIN, Jr. 

